wiki:Tutorials/k0SDR/Tutorial01a

Simple radio example with GNURADIO benchmark scripts

Table of Contents

  1. SDR Tutorials
    1. Working with USRP2 - Universal Software Radio Peripheral
      1. Description
      2. Hardware / Software Resources utilized
      3. Set up
      4. Usage
      5. Capture waveform and record to file & add time-domain plot of waveform
      6. Troubleshooting
    1. Simple radio example with GNURADIO benchmark scripts
      1. Description
      2. Hardware / Software Resources utilized
      3. Set up
      4. Running GNU Radio benchmark scripts
      5. Outputs from transmitter and receiver
      6. Troubleshooting
    1. Simple radio example with GNURADIO benchmark scripts (OEDL)
      1. Description
      2. Hardware / Software Resources utilized
      3. Set up
      4. Running OEDL script and viewing results
      5. OEDL script
    1. OFDM radio example with GNURADIO benchmark scripts
      1. Description
      2. Hardware / Software Resources utilized
      3. Set up
      4. Running OEDL script
    1. Spectrum sensing with USRP2 and wiserd
      1. Description
      2. Hardware / Software Resources utilized
      3. Set up
      4. Generate signal source file using octave
      5. Set up transmitting node
      6. Set up receiving node(s)
    1. Spectrum sensing with USRP2 and wiserd (OEDL and OML)
      1. Description
      2. Hardware / Software Resources utilized
      3. Transmit predefined tone
      4. Record spectrum data to an OML file
      5. Performing the experiment using OEDL
    1. Transmitting wideband signals using USRP X310 and wiserd
      1. Description
      2. Transmitting a signal using wiserd
      3. Creating the signal
    1. Running DSC match script from the grid console
    1. Working with GNURadio and Nutaq ZeptoSDR
      1. Description
      2. Set up
      3. Run the GRC scripts
    1. Realtek 2832 EZCap - A Frugal SDR
      1. Prereqs
      2. A cheap spectrum analyzer
    1. MacSwitch (Obsolete)
      1. Prerequisites
      2. Start Mac Switch
    1. Zynq-based WISER platform - Start-up test
      1. Description
      2. Hardware / Software Resources utilized
      3. Set up
      4. Loading the Zedboard
      5. Running a start up test
    1. Zynq-based WISER platform - Spectrum Sensing
      1. Description
      2. Hardware / Software Resources utilized
      3. Set up
      4. Start spectrum sensing
    1. Zynq-based WISER platform - Spectrum sensing with multiple nodes (OEDL)
      1. Description
      2. Hardware / Software Resources utilized
      3. Spectrum sensing with an OEDL script
    1. Zynq-based WISER platform - Building the Firmware
      1. Description
      2. Getting the FPGA source code
      3. Building the FPGA design
      4. Building ARM core software
    1. Nutaq - PicoSDR start-up and configuration
      1. Description
      2. Set up
      3. Launch demo scripts
    1. Multi channel sample collection with x310
      1. Description
      2. Set up
      3. Collect samples
    1. Getting started with RFNoC X310
      1. Description
      2. Set up
      3. Find USRP X310s
      4. Program the FPGA
    1. Multi Channel Sample Processing & Visualization
      1. Hardware / software resources utilized
      2. Receive multi channel signal for processing and plotting
      3. Transmit a signal using a single usrp
    2. Plot the IQ Constellation of received signal
      1. Multi-channel Uhd STreamer (MUST)
      2. Description
      3. How it works (without going into the source-code :-D
      4. Source code & compilation
      5. Hardware interface application
      6. XML file
      7. Command server
      8. Usage Example
      9. Signal handler applications
      10. Tutorials
    1. Using two RFNoC streams simultaneously on a single USRP device
      1. Description
      2. Set Up
      3. Running the Simulation
    1. Using 2 transmit or 2 receive antennas simultaneously
      1. Description
      2. Set Up
      3. Running the Experiment
    1. Generate random transmissions emulating Primary Transmitters
      1. Description
      2. Set Up
      3. Running the Experiment

Description

This short example will utilize GNU Radio benchmarks scripts to transfer packets over a radio link between two nodes.

Hardware / Software Resources utilized

  1. Grid nodes with a USRP2 connect via Ethernet.
  2. baseline-sdr.ndz: disk image loaded onto nodes. This image has all the precompiled - software required to configure the USRP2s and all the required GNU Radio software libraries. The USRP2's interface with the node is already configured.
  3. GNU Radio - software library to create SDR. Click here for additional info.
  4. USRP2 - hardware platform for SDR. Click here for more info.

Set up

  • Login into reserved domain: ssh username@grid.orbit-lab.org

    Login into reserved domain

    During your approved time slot, you will be able to ssh into the console of the respective domain. A console is a dedicated machine that allows access to all resources in that domain.

    For example, to access the sandbox1:

    yourhost>ssh username@console.sb1.orbit-lab.org
    
    Using username "username".
    Authenticating with public key "xxxxxxxxx"
    Welcome to Ubuntu 12.04.1 LTS (GNU/Linux 3.2.0-36-generic x86_64)
    
     * Documentation:  https://help.ubuntu.com/
    
      System information as of Mon Jan 28 20:25:50 EST 2013
    
      System load:  0.0               Processes:           93
      Usage of /:   2.7% of 69.43GB   Users logged in:     0
      Memory usage: 6%                IP address for eth0: 10.50.18.10
      Swap usage:   0%                IP address for eth1: 10.18.0.10
    
      Graph this data and manage this system at https://landscape.canonical.com/
    
    9 packages can be updated.
    0 updates are security updates.
    
    |-----------------------------------------------------------------|
    |                 *** For authorized use only ***                 |
    | This system is for the use of authorized users only.  All users |
    | are expected to comply with the "Acceptable Use Policy" availa- |
    | ble at http://www.orbit-lab.org/AUP.html                        |
    | Individuals using this computer system, are subject to having   |
    | all of their activities on this system monitored and recorded   |
    | by system personnel.                                            |
    |                                                                 |
    | Anyone using this system expressly consents to such monitoring  |
    | and is advised that if such monitoring reveals possible         |
    | evidence of criminal activity, system personnel may provide the |
    | evidence of such monitoring to law enforcement officials.       |
    |                                                                 |
    | Email question, comments or problems to help@orbit-lab.org      |
    |-----------------------------------------------------------------|
    
    username@console.sb1:~$ 
    
  • Load an image on the nodes: omf load -i baseline-sdr.ndz -t node19-19,node20-20

    Load an Image

    1. Before we begin using the nodes, it's a good idea to check their status first. This is done with the omf stat command.

      omf stat

      This omf command is used to display the power status of the node/domain.

      Usage: omf help stat

      username@consoles.outdoor:omf-5.4 help stat
      Returns the status of the nodes in a testbed
      Usage:
            omf-5.4 stat [-h] [-s] [-t TOPOLOGY] [-c AGGREGATE]
       
            With: 
            -h, --help                print this help message
            -s, --summary             print a summary of the node status for the testbed
            -c, --config AGGREGATE    use testbed AGGREGATE
            -t, --topology TOPOLOGY   a valid topology file or description (defaults to 'system:topo:all')
       
            Some Examples: 
                          omf-5.4 stat
                          omf-5.4 stat -s
                          omf-5.4 stat -t omf.nicta.node1,omf.nicta.node2 -c sb1
                          omf-5.4 stat -t system:topo:all -c grid
      

      Individual nodes are identified in the output of stat command by their fully qualified domain name (FQDN). This establishes their "coordinates" and the "domain" to which they belong. Nodes in different domains typically can NOT see each other. Node can be in 1 of 3 states:

      POWEROFF Node is Available for use but turned off
      POWERON Node is Available and is on
      NOT REGISTERED Node is not Available for use

      Example: omf stat on the outdoor domain

      user@console.outdoor:~# omf stat
      
       INFO NodeHandler: OMF Experiment Controller 5.4 (git 6d34264)
       INFO NodeHandler: Slice ID: default_slice (default)
       INFO NodeHandler: Experiment ID: default_slice-2012-10-14t14.42.15-04.00
       INFO NodeHandler: Message authentication is disabled
       INFO Experiment: load system:exp:stdlib
       INFO property.resetDelay: value = 210 (Fixnum)
       INFO property.resetTries: value = 1 (Fixnum)
       INFO Experiment: load system:exp:eventlib
       INFO Experiment: load system:exp:stat
       INFO Topology: Loading topology ''.
       INFO property.nodes: value = "system:topo:all" (String)
       INFO property.summary: value = false (FalseClass)
       INFO Topology: Loading topology 'system:topo:all'.
       Talking to the CMC service, please wait
      -----------------------------------------------
       Domain: outdoor.orbit-lab.org
       Node: node3-6.outdoor.orbit-lab.org   	 State: NOT REGISTERED
       Node: node3-3.outdoor.orbit-lab.org   	 State: POWEROFF
       Node: node2-10.outdoor.orbit-lab.org    State: POWEROFF
       Node: node1-10.outdoor.orbit-lab.org    State: POWEROFF
       Node: node1-8.outdoor.orbit-lab.org   	 State: POWERON
       Node: node1-6.outdoor.orbit-lab.org   	 State: POWERON
       Node: node3-2.outdoor.orbit-lab.org   	 State: POWEROFF
       Node: node3-1.outdoor.orbit-lab.org   	 State: POWEROFF
       Node: node1-3.outdoor.orbit-lab.org   	 State: POWERON
       Node: node3-5.outdoor.orbit-lab.org   	 State: POWEROFF
       Node: node2-5.outdoor.orbit-lab.org   	 State: NOT REGISTERED
       Node: node1-2.outdoor.orbit-lab.org   	 State: POWERON
      -----------------------------------------------
       INFO Experiment: Switching ON resources which are OFF
       INFO EXPERIMENT_DONE: Event triggered. Starting the associated tasks.
       INFO NodeHandler: 
       INFO NodeHandler: Shutting down experiment, please wait...
       INFO NodeHandler: 
       INFO run: Experiment default_slice-2012-10-14t14.42.15-04.00 finished after 0:6
      

    2. It is recommended that the node be in the POWEROFF state prior to any experiment process. If the node is in the POWERON state you can use the omf tell command to get the node into the off state.

      omf tell

      OMF command to control the power state/reset the nodes.

      Usage: omf help tell

      user@console:omf help tell
      Switch ON/OFF and reboot the nodes in a testbed
      Usage:
            omf tell [-h] -t TOPOLOGY -a ACTION [-c AGGREGATE]
       
            With: 
            -h, --help           print this help message
       
            -a, --action ACTION  specify an action
            ACTION:
            on              turn node(s) ON
            offs            turn node(s) OFF (soft)
            offh            turn node(s) OFF (hard)
            reboot          reboots node(s) (soft)
            reset           resets node(s) (hard)
       
            -h, --help                print this help message
            -t, --topology TOPOLOGY   a valid topology file or description (MANDATORY)
            -c, --config AGGREGATE    use testbed AGGREGATE
       
            Some Examples: 
                          omf tell -a reset -t node1-1.grid.orbit-lab.org
                          omf tell -a on -t system:topo:all -c grid
                          omf tell -a reboot -t node1-1
                          omf tell -a offh -t [1..2,1..5]
                          omf tell -a offh -t system:topo:all
                          omf tell -a reset -t system:topo:imaged
      

      The commands are: on, offh (equivalent to pulling out the power cord), offs (software shutdown), reboot (software reboot) and reset (hardware reset).

      Example: turn off node1-1 on the outdoor domain

      user@console.outdoor:~# omf tell -a offh -t node1-1
      
       INFO NodeHandler: OMF Experiment Controller 5.4 (git 3fb37b9)
       INFO NodeHandler: Reading configuration file /etc/omf-expctl-5.4/services.yaml
       INFO NodeHandler: Add domain http - http://internal1.orbit-lab.org:5054/
       INFO NodeHandler: Add domain http - http://repository1.orbit-lab.org:5054/
       INFO NodeHandler: Slice ID: default_slice (default)
       INFO NodeHandler: Experiment ID: default_slice-2014-09-30t00.24.28.504-04.00
       INFO NodeHandler: Message authentication is disabled
       INFO Experiment: load system:exp:stdlib
       INFO property.resetDelay: resetDelay = 230 (Fixnum)
       INFO property.resetTries: resetTries = 1 (Fixnum)
       INFO Experiment: load system:exp:eventlib
       INFO Experiment: load system:exp:winlib
       INFO Experiment: load system:exp:tell
       INFO property.nodes: nodes = "node1-1" (String)
       INFO property.command: command = "offh" (String)
      
      Talking to the CMC service, please wait
      -----------------------------------------------
       Node: node1-1.outdoor.orbit-lab.org   	 Reply: OK
      -----------------------------------------------
      
       INFO EXPERIMENT_DONE: Event triggered. Starting the associated tasks.
       INFO NodeHandler: 
       INFO NodeHandler: Shutting down experiment, please wait...
       INFO NodeHandler: 
       INFO run: Experiment default_slice-2014-09-30t00.24.28.504-04.00 finished after 0:10
      

    3. Once node set is on an POWEROFF state, load an image with omf load command

      omf load

      Load command is used to put an image onto the hard disk of the node.

      Usage: omf help load

      Install a given disk image on the nodes in a testbed
      Usage:
            omf-5.4 load [-h] [-i IMAGE_PATH] [-o TIMEOUT] [-t TOPOLOGY] [-c AGGREGATE]
       
            With: 
            -h, --help                print this help message
            -c, --config AGGREGATE    use testbed AGGREGATE
            -t, --topology TOPOLOGY   a valid topology file or description (defaults to 'system:topo:all')
                                      (if a file 'TOPOLOGY' doesn't exist, interpret it as a comma-separated list of nodes)
            -i, --image IMAGE         disk image to load
                                      (default is 'baseline.ndz', the latest stable baseline image)
            -o, --timeout TIMEOUT     a duration (in sec.) after which imageNodes should stop waiting for
                                      nodes that have not finished their image installation
                                      (default is 800 sec, i.e. 13min 20sec)
                --outpath PATH        Path where the resulting Topologies should be saved
                                      (default is '/tmp')
                --outprefix PREFIX    Prefix to use for naming the resulting Topologies
                                      (default is your experiment ID)
       
            Some Examples: 
                          omf-5.4 load
                          omf-5.4 load -t system:topo:all -i baseline-2.4.ndz
                          omf-5.4 load -t omf.nicta.node1 -i wireless-2.6.ndz
                          omf-5.4 load -t omf.nicta.node1,omf.nicta.node2 -i baseline.ndz -o 400
                          omf-5.4 load -t system:topo:circle -i my_Own_Image.ndz
                          omf-5.4 load -t my_Own_Topology -i baseline-2.2.ndz -t 600 -c grid
                          omf-5.4 load -t my_Own_Topology --outpath ./ --outprefix my_Own_Prefix
      

      Two important arguments are TOPOLOGY describing the set of nodes one wishes to image , and !IMAGE specifying the name of the image one wants to load the nodes with. If the imaging process does not does not finish within the default timeout period, that period can be increase by using the -o flag (e.g. -o 1600). Typical command to load both nodes of sandbox 1 with the baseline? image would look like:

      Example: omf load-i baseline.ndz -t system:topo:all

      username@console.sb7:~$ omf load -t all -i baseline.ndz
      
       INFO NodeHandler: OMF Experiment Controller 5.4 (git c005675)
       INFO NodeHandler: Slice ID: pxe_slice 
       INFO NodeHandler: Experiment ID: pxe_slice-2013-01-16t14.56.02-05.00
       INFO NodeHandler: Message authentication is disabled
       INFO Experiment: load system:exp:stdlib
       INFO property.resetDelay: resetDelay = 230 (Fixnum)
       INFO property.resetTries: resetTries = 1 (Fixnum)
       INFO Experiment: load system:exp:eventlib
       INFO Experiment: load system:exp:imageNode
       INFO property.nodes: nodes = "system:topo:all" (String)
       INFO property.image: image = "baseline.ndz" (String)
       INFO property.domain: domain = "sb7.orbit-lab.org" (String)
       INFO property.outpath: outpath = "/tmp" (String)
       INFO property.outprefix: outprefix = "pxe_slice-2013-01-16t14.56.02-05.00" (String)
       INFO property.timeout: timeout = 800 (Fixnum)                                                                                          
       INFO property.resize: resize = nil (NilClass)
       INFO Topology: Loading topology 'system:topo:all'.
       INFO Experiment: Resetting resources
       INFO stdlib: Waiting for nodes (Up/Down/Total): 0/2/2 - (still down: node1-2.sb7.orbit-lab.org,node1-1.sb7.orbit-lab.org) [0 sec.]
       INFO stdlib: Waiting for nodes (Up/Down/Total): 0/2/2 - (still down: node1-2.sb7.orbit-lab.org,node1-1.sb7.orbit-lab.org) [10 sec.]
       INFO stdlib: Waiting for nodes (Up/Down/Total): 0/2/2 - (still down: node1-2.sb7.orbit-lab.org,node1-1.sb7.orbit-lab.org) [20 sec.]
       INFO stdlib: Waiting for nodes (Up/Down/Total): 0/2/2 - (still down: node1-2.sb7.orbit-lab.org,node1-1.sb7.orbit-lab.org) [30 sec.]
       INFO ALL_UP: Event triggered. Starting the associated tasks. 
       INFO exp: Progress(0/0/2): 0/0/0 min(node1-2.sb7.orbit-lab.org)/avg/max (30) - Timeout: 760 sec.
       INFO exp: Progress(0/0/2): 10/10/10 min(node1-2.sb7.orbit-lab.org)/avg/max (30) - Timeout: 750 sec.
       INFO exp: Progress(0/0/2): 10/15/20 min(node1-1.sb7.orbit-lab.org)/avg/max (30) - Timeout: 740 sec.
       INFO exp: Progress(0/0/2): 20/25/30 min(node1-2.sb7.orbit-lab.org)/avg/max (30) - Timeout: 730 sec.
       INFO exp: Progress(0/0/2): 30/35/40 min(node1-1.sb7.orbit-lab.org)/avg/max (30) - Timeout: 720 sec.
       INFO exp: Progress(0/0/2): 40/40/40 min(node1-2.sb7.orbit-lab.org)/avg/max (30) - Timeout: 710 sec.
       INFO exp: Progress(0/0/2): 40/45/50 min(node1-1.sb7.orbit-lab.org)/avg/max (30) - Timeout: 700 sec.
       INFO exp: Progress(0/0/2): 50/55/60 min(node1-1.sb7.orbit-lab.org)/avg/max (30) - Timeout: 690 sec.
       INFO exp: Progress(0/0/2): 60/65/70 min(node1-1.sb7.orbit-lab.org)/avg/max (30) - Timeout: 680 sec.
       INFO exp: Progress(0/0/2): 60/65/70 min(node1-1.sb7.orbit-lab.org)/avg/max (30) - Timeout: 670 sec.
       INFO exp: Progress(0/0/2): 70/75/80 min(node1-2.sb7.orbit-lab.org)/avg/max (30) - Timeout: 660 sec.
       INFO exp: Progress(0/0/2): 90/90/90 min(node1-2.sb7.orbit-lab.org)/avg/max (30) - Timeout: 650 sec.
       INFO exp: Progress(1/0/2): 90/95/100 min(node1-1.sb7.orbit-lab.org)/avg/max (30) - Timeout: 640 sec.
       INFO exp: Progress(2/0/2): 100/100/100 min()/avg/max (30) - Timeout: 630 sec.
       INFO exp:  ----------------------------- 
       INFO exp:  Imaging Process Done 
       INFO exp:  2 nodes successfully imaged - Topology saved in '/tmp/pxe_slice-2013-01-16t14.56.02-05.00-topo-success.rb'
       INFO exp:  ----------------------------- 
       INFO EXPERIMENT_DONE: Event triggered. Starting the associated tasks.
       INFO NodeHandler: 
       INFO NodeHandler: Shutting down experiment, please wait...
       INFO NodeHandler: 
       INFO NodeHandler: Shutdown flag is set - Turning Off the resources
       INFO run: Experiment pxe_slice-2013-01-16t14.56.02-05.00 finished after 3:13
      

      If the node is in the NOT REGISTERED state, you may need to wait for it to recover the POWEROFF state (it some times requires a few moments for the services to sync up). If the node takes more than 60 seconds to come out of the NODE NOT AVAILABLE state please report it to an administrator.
  • Turn on the nodes: omf tell -a on -t node19-19,node20-20

    Turn the Nodes ON

    To turn the nodes on use omf tell command:

    omf tell

    OMF command to control the power state/reset the nodes.

    Usage: omf help tell

    user@console:omf help tell
    Switch ON/OFF and reboot the nodes in a testbed
    Usage:
          omf tell [-h] -t TOPOLOGY -a ACTION [-c AGGREGATE]
     
          With: 
          -h, --help           print this help message
     
          -a, --action ACTION  specify an action
          ACTION:
          on              turn node(s) ON
          offs            turn node(s) OFF (soft)
          offh            turn node(s) OFF (hard)
          reboot          reboots node(s) (soft)
          reset           resets node(s) (hard)
     
          -h, --help                print this help message
          -t, --topology TOPOLOGY   a valid topology file or description (MANDATORY)
          -c, --config AGGREGATE    use testbed AGGREGATE
     
          Some Examples: 
                        omf tell -a reset -t node1-1.grid.orbit-lab.org
                        omf tell -a on -t system:topo:all -c grid
                        omf tell -a reboot -t node1-1
                        omf tell -a offh -t [1..2,1..5]
                        omf tell -a offh -t system:topo:all
                        omf tell -a reset -t system:topo:imaged
    

    The commands are: on, offh (equivalent to pulling out the power cord), offs (software shutdown), reboot (software reboot) and reset (hardware reset).

    Example: turn off node1-1 on the outdoor domain

    user@console.outdoor:~# omf tell -a offh -t node1-1
    
     INFO NodeHandler: OMF Experiment Controller 5.4 (git 3fb37b9)
     INFO NodeHandler: Reading configuration file /etc/omf-expctl-5.4/services.yaml
     INFO NodeHandler: Add domain http - http://internal1.orbit-lab.org:5054/
     INFO NodeHandler: Add domain http - http://repository1.orbit-lab.org:5054/
     INFO NodeHandler: Slice ID: default_slice (default)
     INFO NodeHandler: Experiment ID: default_slice-2014-09-30t00.24.28.504-04.00
     INFO NodeHandler: Message authentication is disabled
     INFO Experiment: load system:exp:stdlib
     INFO property.resetDelay: resetDelay = 230 (Fixnum)
     INFO property.resetTries: resetTries = 1 (Fixnum)
     INFO Experiment: load system:exp:eventlib
     INFO Experiment: load system:exp:winlib
     INFO Experiment: load system:exp:tell
     INFO property.nodes: nodes = "node1-1" (String)
     INFO property.command: command = "offh" (String)
    
    Talking to the CMC service, please wait
    -----------------------------------------------
     Node: node1-1.outdoor.orbit-lab.org   	 Reply: OK
    -----------------------------------------------
    
     INFO EXPERIMENT_DONE: Event triggered. Starting the associated tasks.
     INFO NodeHandler: 
     INFO NodeHandler: Shutting down experiment, please wait...
     INFO NodeHandler: 
     INFO run: Experiment default_slice-2014-09-30t00.24.28.504-04.00 finished after 0:10
    

Running GNU Radio benchmark scripts

  • From two different terminals ssh into node19-19 and node20-20. Then change to the benchmark script's directory. For this example use node19-19 as the receiver and node20-20 as the transmitter.
    username@console.grid:~$ ssh root@node19-19
    root@node19-19:~# cd gnuradio/gr-digital/examples/narrowband
    
  • Start the receiver benchmark script
    root@node19-19:~/gnuradio/gr-digital/examples/narrowband# ./benchmark_rx.py -f 2.41G -m bpsk --rx-gain 10 -r .250M
    
    The parameters passed to the receiving script are as follows:

'-f 2.41G' ———> the carrier frequency to 2.41GHz

'-m bpsk' ———> the modulation mode to binary phase shift keying.

'-r .250M' ———> the bitrate to 250000 bits /sec

'—rx-gain 10' —> receiver front end gain to 10dB.

  • Start the transmitter benchmark script
    root@node20-20:~/gnuradio/gr-digital/examples/narrowband# ./benchmark_tx.py -f 2.41G -m bpsk --tx-gain 10 -r .250M --tx-amplitude .5
    
    The values passed to the transmitting script must be similar to the receiver script with the exception of radio specific parameters.

'—tx-gain 10' —> transmitter front end gain to 10dB.

Outputs from transmitter and receiver

  • Once a successful radio link has been established, the transmitted packets are received, decoded and verify by the gnu scripts. A sample output of the receiver is shown below.
    root@node19-19:~/gnuradio/gr-digital/examples/narrowband# ./benchmark_rx.py -f 2.41G -m bpsk --rx-gain 10 -r .250M
    linux; GNU C++ version 4.8.2; Boost_105400; UHD_003.008.002-86-g566dbc2b
    
    Using Volk machine: avx_64_mmx_orc
    -- Opening a USRP2/N-Series device...
    -- Current recv frame size: 1472 bytes
    -- Current send frame size: 1472 bytes
    ok =  True  pktno =    1  n_rcvd =    1  n_right =    1
    ok =  True  pktno =    2  n_rcvd =    2  n_right =    2
    ok =  True  pktno =    3  n_rcvd =    3  n_right =    3
    ok =  True  pktno =    4  n_rcvd =    4  n_right =    4
    ok =  True  pktno =    5  n_rcvd =    5  n_right =    5
    ok =  True  pktno =    6  n_rcvd =    6  n_right =    6
    ok =  True  pktno =    7  n_rcvd =    7  n_right =    7
    ok =  True  pktno =    8  n_rcvd =    8  n_right =    8
    ok =  True  pktno =    9  n_rcvd =    9  n_right =    9
    ok =  True  pktno =   10  n_rcvd =   10  n_right =   10
    ok =  True  pktno =   11  n_rcvd =   11  n_right =   11
    ok =  True  pktno =   12  n_rcvd =   12  n_right =   12
    ok =  True  pktno =   13  n_rcvd =   13  n_right =   13
    ok =  True  pktno =   14  n_rcvd =   14  n_right =   14
    ok =  True  pktno =   15  n_rcvd =   15  n_right =   15
    ok =  True  pktno =   16  n_rcvd =   16  n_right =   16
    ok =  True  pktno =   17  n_rcvd =   17  n_right =   17
    ok = False  pktno =   18  n_rcvd =   18  n_right =   17
    ^C
    

For the transmitter output should be similar to this:

root@node20-20:~/gnuradio/gr-digital/examples/narrowband# ./benchmark_tx.py -f 2.41G -m bpsk --tx-gain 10 -r .250M --tx-amplitude .5
linux; GNU C++ version 4.8.2; Boost_105400; UHD_003.008.002-86-g566dbc2b

Using Volk machine: sse4_2_64_orc
-- Opening a USRP2/N-Series device...
-- Current recv frame size: 1472 bytes
-- Current send frame size: 1472 bytes
................................................................................................................................................................................................................................................................................................................................................................................................................................................^C

Troubleshooting

  • If the receiving script is not showing any activity, it most likely the script parameters need to be tweaked. USRP radios (any radio in general) are not made the same due to variations in HW component quality and tolerances. Each radio has it's own sweet spot for best transmission and reception. For different USRPs on the grid (or other sandboxes) raising or lowering gains, amplitude, and/or other parameters is required to establish a solid radio link.

As an example if the gains are set too hi, signal can become saturated, clipped and distort at the analog-digital interface. If the gains are set too low, the signal will just blend in to the noise floor especially for simple modulation schemes. For a description of other parameters, use the —help command get a listing.

root@node19-19:~/gnuradio/gr-digital/examples/narrowband# ./benchmark_rx.py --help
  • To check the signal at the receiver, use the 'rx_ascii_art_dft' utility provided by UHD to view the spectrum:
    root@node19-19:~/gnuradio/gr-digital/examples/narrowband# /root/uhd/host/build/examples/rx_ascii_art_dft --freq 2.41e9 --rate 5e6 --gain 5 --ref-lvl -40
    
Last modified 6 weeks ago Last modified on 06/12/17 17:02:56